1. Field of the Invention
This invention relates to a conductive thermosettable dispersion composition which, on heating at or above the plasticization temperature, rapidly provides a conductive thermoset material with improved conductivity usable as an ink, adhesive, gasket, sealant or in EMI and RF shielding.
The invention also relates to a process for forming a conductive crosslinked bond or seal.
2. Description of the Prior Art
Conductive coatings are known in the art.
U.S. Pat. No. 3,412,043 teaches an electrically conductive resinous composition consisting essentially of silver flake, resinous binder and finally divided inert filler in specified weight ratios. Therein one resinous binder is an epoxy resin system which is cured by the addition of an amine curing agent at slightly elevated temperatures.
U.S. Pat. No. 3,746,662 teaches electrically conductive coatings comprising certain epoxy resins, particles of tough polymer having carboxy, hydroxy, amino or isocyanate substituents which are grafted by the epoxy resin at the interface, finely divided metal particles and a curing agent for the epoxy resin. The curing is obtained by heating the composition at temperatures of 125.degree. C. or higher.
U.S. Pat. No. 3,968,056 teaches a radiation curable ink comprising a particulated electrically conductive metal containing material in combination with an organic resin binder which is converted to a conductive coating on the surface of a substrate by exposure to either actinic or ionizing radiation.
U.S. Pat. No. Re. 30,274 teaches a circuit board for activating high voltage flashlamps, said board including a non-conductive, thermoplastic substrate having a patterned electrically conductive coating on one of its surfaces and defining electrical circuitry for the flashlamps, said coating comprising an organic resin matrix curable by UV radiation and a particulated electrically conductive material selected from the group consisting of a particulated electrically conductive metal and a particulated electrically conductive metal containing material, including mixtures thereof with no more than up to about 15% by weight of said particulated electrically conductive material having an aspect ratio of diameter to thickness of a value greater than 20.
U.S. Pat. No. 3,609,104 teaches the use of compressible, non-flowable particles to promote the conductivity of the conductive plastic. The flowable resin is one that chemically bonds to the surface of the non-flowable particles when it is hardened. During hardening, sufficient pressure is applied to distort the non-flowable particles to induce a conductive web from the conductive filler. For this purpose the non-flowable particles must be compressible.